1 Technical Field
This disclosure relates generally to an ignition coil for an internal combustion engine.
2 Background Art
For instance, Japanese Patent No. 5340889 discloses an ignition coil which includes a primary coil, a secondary coil, and a case. The primary and secondary coils are magnetically coupled with each other and disposed inside the case. The case is filled with resin to hermetically seal the primary and secondary coils. The case also has disposed therein a resistor which closes a front open end of the case in order to avoid leakage of the filled resin outside the case. This also results in a decrease in the number of parts of the ignition coil.
The ignition coil is so designed as to press-fit the resistor directly into the front open end of the case and, therefore, faces the drawback in that the resistor may be too large in size to be inserted into the open end of the case depending upon, for example, an error in machining the resistor or mechanical stress arising from the press-fitting of the resistor into the open end of the case may be undesirably increased, which leads to damage to or breakage of the case. Alternatively, too small a size of the resistor may result in a failure to be tightly fitted into the open end of the case, which leads to escape of the resin outside the case when the resin is packed into the case. Therefore, the ignition coil which is designed to have the resistor press-fit into the open end of the case requires high accuracy in machining the resistor and the open end of the case.